Circular saw with means for opening up the cut slit

ABSTRACT

A cutting tool arrangement for performing the process of opening up the slit cut in the workpiece by circular saws before the saw is retracted to facilitate removal of the saw. The workpiece being severed is moved perpendicular to the cutting plane as is the saw blade to accomplish the desired result.

The invention relates to a cutting tool arrangement for use in theprocess of opening up the slit, cut in workpieces by circular saws,before the retraction of the saw blade and after the sawing step.

A process of this type serves to protect the saw blade from unnecessarywear which would occur if the saw blade were retracted again through thecut slit which has just been sawn. For this purpose, the severed part ofthe workpiece is moved away perpendicular to the plane of cutting andthe saw spindle together with the saw blade is then laterally displacedin the same direction, but not to the same extent.

In conventional processes, opening up of the cut slit is achieved insuch a way that, on the one hand, the clamping, such as a chuck holder,for the severed part of the workpiece is moved away from the saw blade,parallel to the axis of rotation of the saw blade, by means of a pullingdevice and that, on the other hand, the saw blade together with the sawspindle in its bearings in the drive housing is then axially shifted bythe requisite distance.

A disadvantage of this procedure is that, for displacing or shifting thesaw spindle, a displaceable rotary connection between the saw spindleand the corresponding associated shifting device is required, as aresult of which the drive mechanism of the saw must be of an extremelycomplicated design in order to be able to ensure vibration-free runningof the saw blade.

It is the object of the invention to provide a process for opening upthe cut slit and a circular saw for carrying out the process, whereindirect transmission of the drive power is made possible while avoidingthis disadvantage.

According to the invention, this object is achieved by laterallydisplacing the drive housing of the disc saw together with the sawspindle and the saw blade as a whole.

Opening up of the cut slit is thus effected in such a way that the partof the workpiece, which has been sawn off, is laterally displaced by acertain distance and the entire drive mechanism of the saw together withthe saw blade is then displaced or shifted in the same direction withthe aid of sequence control, for example by half this distance.Moreover, as a result of the invention, the stress in the bearings isconsiderably reduced by uncoupling the axial movement and thecircumferential movement of the saw spindle.

In circular saws or machine saws, in which the drive mechanism of thesaw is accommodated in a swivel arm, this axial displacement in themounting of the swivel arm can be carried out in a simple manner,preferably hydraulically.

A particular advantage is here that a special design for the drivemechanism is not necessary, but that instead this can be constructed ina manner which is as simple as is determined solely by the sawing step.

The invention is explained in more detail by reference to theillustrative embodiments shown in the drawing in which:

FIG. 1 diagrammatically shows a plan view and a partial section of afirst illustrative embodiment of the invention,

FIG. 2 shows a plan view, similar to FIG. 1, of a second illustrativeembodiment of the invention, and

FIG. 3 shows a side view, in partial section, of a special clampingdevice for the parts of the workpiece.

FIGS. 1 and 2 show a plan view of a part of the machine saw or circularsaw, having a saw table 1 and a swivel arm 2 which contains the drivefor a saw blade 3. A part of material or workpiece 4 fed in is held byclamping jaws 5, whilst the part 6 of the workpiece, which is to be cutoff, is clamped and held by laterally displaceable clamping jaws 7 andcan be moved laterally after it has been severed.

The swivel arm 2 is here mounted on the hydraulic cylinder side in ajournal bearing 8, for example, a cylindrical roller bearing, and ismounted on the saw blade side in a journal bearing and a conical rollerbearing 9, or it is mounted on both sides in both the types of bearing(FIG. 2).

The hydraulic cylinder for shifting the swivel arm 2 has a piston 11which engages on the bearing shaft 10 of the swivel arm 2 and islaterally displaceable in a housing 14, specifically by introducing ahydraulic fluid either via a cylinder opening 12 or a cylinder opening13, which are located in the housing 14 on either side of the piston 11.

During the sawing step, the piston 11 is subject to a constant pressureas a result of the introduction of hydraulic fluid via the opening 12.This pressure on the piston 11 is transmitted via the shaft 10 to atleast one conical roller bearing 9, which is supported on parts15,16,17, in such a way that an axial distortion of the conical rollerbearings 9 relative to the saw table 1 is obtained, as a result of whichradial mounting without play is achieved. In this way, the saw arm 2 ismounted absolutely without play so that a vibration-free oroscillation-free sawing step can be achieved, which is a verysubstantial advantage in sawing.

FIG. 3 shows the device for clamping the work part. The workpiece 4 isintroduced in the direction of the arrow, while the saw is swivelled upor the swivel arm 2 is swivelled up, and is clamped in before the sawingstep by means of the clamping jaws or chuck jaws 5 or 7, which arelocated on either side relative to the cutting slit which is to besawed. The clamping jaw 7 is fixed to a swivel arm 18 which is mountedto be pivotable about a pivot point 19 relative to the saw table 1.Before sawing, the clamping jaws 7 are actuated in their end position onthe right-hand side (FIG. 3), that is to say in their position nearestto the clamping jaws 5, in order to clamp in the workpiece 4. After thestep of chucking or clamping the workpiece 4 has been carried out oneither side of the saw blade 3, a piston 21 in the saw table 1 issubjected via a channel 22 to the constant pressure of a hydraulicfluid. This pressure force is transmitted to the clamping jaws 7, as aresult of which a pre-tension of the section of material or of the part6 of the workpiece, which is to be severed, is obtained during thesawing step.

After the part 6 of the workpiece has been severed, the latter is stillheld by the clamping jaws and is moved laterally, that is to say to theleft in FIG. 3, away from the saw blade 3 by means of the piston 21 dueto the pressure of the hydraulic fluid in the channel 22; this resultsin the cutting channel being opened up.

By means of sequence control, the saw blade housing, that is to say inthe present case the swivel arm containing the arm 7 of the saw blade,as shown in FIGS. 1 and 2, is then laterally displaced in the samedirection, that is to say to the left in FIG. 3; in other words, the sawdrive mechanism including the saw blade 3 is moved away by a fewmillimeters from the cutting point of the workpiece 4 which is clampedin between the clamping jaws 5. The swivel arm 2, together with the sawblade 3, can now be swivelled upwards into the starting position. Theclamping jaws 7 then release the part 6 of the workpiece, which has beensawn off. A further sawing step or further cutting step can then betriggered by appropriate feeding of the workpiece 4.

For this purpose, the swivel arm 18 is returned into the startingposition by means of a piston 24 as a result of subjecting it to thepressure of a hydraulic fluid in passage 23, the channel 22 beingrelieved at the same time.

The essential point of the invention is that the cut slit is opened upreliably and perfectly before the return stroke of the saw blade 3. Thisis assisted by the fact that, due to the swivel movement of the swivelarm 18, the clamping jaws 7 prevent contact of the part 6 of theworkpiece, which has been cut off, with the saw blade 3 without furtherexternal influence, as a result of the heavy weight or of aninward-tilting motion, even if the saw blade is likewise displaced inthe same direction.

Since the swivel movements and displacement movements and, ifappropriate, also the clamping movements are effected hydraulically,sequence control of a simple design can be achieved.

We claim:
 1. An improved cutting tool arrangement for cutting aworkpiece comprising:a movable saw blade, drive means for moving saidsaw blade, arm means for supporting said saw blade and said drive meansand for effecting transverse movement of the saw blade relative to theworkpiece to cut the workpiece into two portions and for effectingretraction of the saw blade relative to the workpiece, means foreffecting movement of one of said workpiece portions away from the otherworkpiece portion, displacement means for displacing said arm meanslaterally of said transverse movement and for moving said saw blade awayfrom the other workpiece portion, and sequencing means for activatingsaid displacement means after said one portion has moved away from saidother portion, whereby said arm means are displaced before said sawblade is retracted to reduce contact of said saw blade with the otherworkpiece portion during retraction.
 2. The cutting tool arrangement asrecited in claim 1, whereinsaid arm means includes pivot means forpivoting said saw blade in an arc defining a plane extending generallyperpendicular to said workpiece.
 3. The cutting tool as recited in claim2, whereinsaid displacement means is aligned with and acts coaxially ofthe pivot axis of said pivot means.
 4. The cutting tool as recited inclaim 1 or 3, wherein,said displacement means comprise a fluid actuator.5. The cutting tool arrangement as recited in claim 1 or 3 whereinsaidmeans for effecting movement of said one workpiece portion maintainssaid workpiece in tension during the cutting of the workpiece by the sawblade.
 6. The cutting tool arrangement as recited in claim 5,whereinsaid means for effecting movement comprises swivel means forpivoting said one workpiece portion relative to said other workpieceportion.
 7. The cutting tool arrangement as recited in claim 6, andsaidswivel means including fluid actuator means for effecting said pivoting.8. The cutting tool arrangement as recited in claim 3, whereinsaid pivotmeans includes thrust bearing means for accommodating displacement ofsaid arm means by said displacement means.
 9. An improved cutting toolarrangement for cutting a workpiece comprising:a rotatable circular sawblade, drive means for rotating said blade, swivel arm means forsupporting said saw blade and said drive means for pivoting movementabout a pivot axis parallel to the axis of rotation of said saw blade,said arm means being pivotal for effecting cutting of said workpieceinto two portions by said saw blade and for retracting said saw bladefrom said workpiece, clamp means for gripping one of said portions andfor moving said one portion away from said other portion, anddisplacement means for displacing said swivel arm means axially of saidpivot axis and away from said other portion after said one portion ismoved and prior to said swivel arm means retracting said saw blade fromsaid workpiece.
 10. The cutting tool arrangement as recited in claim 9,whereinsaid displacement means are disposed such that said swivel arm isdisplaced in generally the same direction as said clamp means move saidone portion.
 11. The cutting tool arrangement as recited in claim 9,andpivot means for pivotally mounting said clamp means for movementabout a clamp pivot axis perpendicular to said pivot axis, said clampmeans maintaining said workpiece in tension during cutting by said sawblade.
 12. The cutting tool arrangement as recited in claims 9 or 11,andhydraulic means for reversibly actuating said clamp means and saiddisplacement means.